
If screened cable is necessary,connect the cable screen on both ends
to ground potential.In the sensor,the screen must be connected
directly to the internal ground terminal.The ground terminal on the
outside of the housing must be connected to the potential equalisation
(low impedance).
If potential equalisation currents are expected,the connection on the
processing side must be made via a ceramic capacitor (e.g.1nF,
1500 V). The low frequency potential equalisation currents are thus
suppressed,but the protective effect against high frequency interfer-
ence signals remains.
Take note of the corresponding installation regulations for Ex
applications.In particular,make sure that no potential equalisation
currents flow over the cable screen.In case of grounding on both sides
this can be achieved by the use of a capacitor or a separate potential
equalisation.
With the Exd version,the minus side of the signal output is galvanically
connected to ground via protective diodes.When connecting the
instrument to a grounded PLC,equalising currents can flow in case of
potential differences which can cause malfunctions.Make sure that
there is sufficient potential equalisation from the system side or realise
the connection via switching amplifier.
5.2Connection procedure
Proceed as follows:
1Unscrew the housing cover
2Loosen compression nut of the cable entry
3Remove approx.10 cm (4in)of the cable mantle (current output),
strip approx.1cm (0.4in)insulation from the ends of the individual
wires
4Insert the cable into the sensor through the cable entry
5Lift the opening levers of the terminals with a screwdriver
6Insert the wire ends into the open terminals according to the wiring
plan
7Press down the opening levers of the terminals,you will hear the
terminal spring closing
8Check the hold of the wires in the terminals by lightly pulling on
them
9Connect the screen to the internal ground terminal,connect the
outer ground terminal to potential equalisation
10 Tighten the compression nut of the cable entry.The seal ring must
completely encircle the cable
11 Connect the lead cable for power supply in the same way
according to the wiring plan,in addition connect the ground
conductor to the inner ground terminal.
Cable screening and
grounding
Installation with
Ex applications
18 VEGAFLEX 66 •4…20 mA/HART four-wire
5Connecting to power supply
34170-EN-100427